The present invention relates to a method of monitoring the operation of a contactor and more specifically to a method of determining the position of an armature of a contactor relative to a stator of the contactor.
The position of an armature of a known contactor relative to a stator of the contactor has previously been determined by sensing changes in the inductance of the coil of the contactor. As the armature of the known contactor is moving toward a closed or actuated position, a plurality of current peaks are established in the coil of the contactor. The decay time of at least some of the current peaks is sensed. When the decay time exceeds the decay time of one or more previously measured current peaks by a selected amount, an inference is made that the inductance of the coil of the known contactor has changed sufficiently to indicate that the contactor has been operated to the actuated condition. A contactor control system which operates in this manner is disclosed in U.S. Pat. No. 5,053,911. Another known contactor control system is disclosed in U.S. Pat. No. 4,833,565.